Light field display control method and apparatus, and light field display device

1. A light field display control method, comprising: determining at least one depth distribution sub-region of content according to a display depth of field (DoF) range of a light field display device and depth distribution information of the content, wherein each depth distribution sub-region of the at least one depth distribution sub-region is located outside the display DoF range; and adjusting a focal length of a first lenslet according to at least the display DoF range and the depth distribution sub-region, wherein the first lenslet is a lenslet that is in a lenslet array of the light field display device and affects display of a first object, and the first object is a part, which is located in the depth distribution sub-region, of the content, wherein, adjusting the focal length of the first lenslet includes: determining, according to an expected focal length of the first lenslet, a phase difference that is formed after incident light passes through different parts of the first lenslet; determining, according to a mapping relationship between phase differences and external fields, an external field corresponding to the phase difference; and changing, by means of the external field, the phase difference that is formed after the incident light passes through the different parts of the first lenslet to adjust the focal length of the first lenslet.

2. The method of claim 1 , wherein an average circle of confusion, in a first display plane of the light field display device, of the first lenslet whose focal length has been adjusted is less than or equal to a permissible circle of confusion, and the first display plane is a display plane that is corresponding to a focusing distance for viewing in a depth direction and perpendicular to the depth direction.

3. The method of claim 1 , wherein at least one of the at least one depth distribution sub-region is continuous in terms of depth with the display DoF range.

4. The method of claim 1 , wherein at least one of the at least one depth distribution sub-region is discontinuous in terms of depth with the display DoF range.

5. The method of claim 1 , wherein the adjusting a focal length of a first lenslet according to at least the display DoF range and the depth distribution sub-region comprises: determining expected display depth information of the first object according to at least the display DoF range; and adjusting the focal length of the first lenslet according to at least the expected display depth information.

6. The method of claim 5 , wherein the determining expected display depth information of the first object according to at least the display DoF range comprises: determining any display depth in the display DoF range as the expected display depth information of the first object.

7. The method of claim 5 , wherein the determining expected display depth information of the first object according to at least the display DoF range comprises: determining a display depth, which is in the display DoF range and close to the depth distribution sub-region, as the expected display depth information of the first object according to a relative distribution of the depth distribution sub-region and the display DoF range in the depth direction.

8. The method of claim 5 , wherein the adjusting the focal length of the first lenslet according to at least the expected display depth information comprises: determining the expected focal length of the first lenslet according to the expected display depth information and a distance between a monitor and the lenslet array in the light field display device; and adjusting the focal length of the first lenslet according to at least the expected focal length.

9. The method of claim 1 , wherein the first lenslet is a first liquid crystal lenslet; and the determining, according to at least the expected focal length, a phase difference that is formed after incident light passes through different parts of the first lenslet comprises: determining, according to the expected focal length, a radius of the first liquid crystal lenslet, and a wavelength of the incident light, a phase difference that is formed after the incident light passes through different parts of the first liquid crystal lenslet.

10. The method of claim 8 , wherein the adjusting the focal length of the first lenslet according to at least the expected focal length comprises: determining a permissible focal length adjustment range of the first lenslet according to at least the expected focal length; and adjusting the focal length of the first lenslet according to at least the permissible focal length adjustment range.

11. The method of claim 10 , wherein the adjusting the focal length of the first lenslet according to at least the permissible focal length adjustment range comprises: determining, according to the permissible focal length adjustment range, a permissible phase difference range that is formed after incident light passes through different parts of the first lenslet; determining, according to a mapping relationship between phase differences and external fields, an external field corresponding to a permissible phase difference in the permissible phase difference range; and changing, by means of the external field, a phase difference that is formed after the incident light passes through the different parts of the first lenslet, so as to adjust the focal length of the first lenslet.

12. The method of claim 11 , wherein the first lenslet is a first liquid crystal lenslet; and the determining, according to the permissible focal length adjustment range, a permissible phase difference range that is formed after incident light passes through different parts of the first lenslet comprises: determining, according to a maximum permissible focal length in the permissible focal length adjustment range, a radius of the first liquid crystal lenslet, and a wavelength of the incident light, a first phase difference that is formed after the incident light passes through different parts of the first liquid crystal lenslet; determining, according to a minimum permissible focal length in the permissible focal length adjustment range, the radius of the first liquid crystal lenslet, and the wavelength of the incident light, a second phase difference that is formed after the incident light passes through different parts of the first liquid crystal lenslet; and determining the permissible phase difference range according to the first phase difference and the second phase difference.

13. The method of claim 1 , wherein before the first lenslet is adjusted, the method further comprises: determining a lenslet which is in the lenslet array and affects display of the first object as the first lenslet.

14. The method of claim 13 , wherein the determining a lenslet which is in the lenslet array and affects display of the first object as the first lenslet comprises: determining a first display sub-region according to expected display depth information, a focusing distance for viewing, and a pupil size of a human eye, wherein the first display sub-region is a display sub-region that is in the monitor of the light field display device and affects display of the first object; and determining, according to a mapping relationship between display sub-regions in the monitor and lenslets in the lenslet array, a lenslet which is in the lenslet array and corresponding to the first display sub-region as the first lenslet.

15. A non-transitory computer-readable storage medium configured with instructions executable by one or more processors to cause the one or more processors to perform operations comprising: determining at least one depth distribution sub-region of content according to a display depth of field (DoF) range of a light field display device and depth distribution information of the content, wherein each depth distribution sub-region of the at least one depth distribution sub-region is located outside the display DoF range; and adjusting a focal length of a first lenslet according to at least the display DoF range and the depth distribution sub-region, wherein the first lenslet is a lenslet that is in a lenslet array of the light field display device and affects display of a first object, and the first object is a part, which is located in the depth distribution sub-region, of the content, wherein, adjusting the focal length of the first lenslet includes: determining, according to an expected focal length of the first lenslet, a phase difference that is formed after incident light passes through different parts of the first lenslet; determining, according to a mapping relationship between phase differences and external fields, an external field corresponding to the phase difference; and changing, by means of the external field, the phase difference that is formed after the incident light passes through the different parts of the first lenslet to adjust the focal length of the first lenslet.

16. A light field display control apparatus, comprising: a processor, a communications interface, a memory, and a communications bus, wherein the processor, the communications interface, and the memory communicate with each other by means of the communications bus; the memory is configured to store at least one instruction, and the at least one instruction causes the processor to perform operations including: determining at least one depth distribution sub-region of content according to a display depth of field (DoF) range of a light field display device and depth distribution information of the content, wherein each depth distribution sub-region of the at least one depth distribution sub-region is located outside the display DoF range; and adjusting a focal length of a first lenslet according to at least the display DoF range and the depth distribution sub-region, wherein the first lenslet is a lenslet that is in a lenslet array of the light field display device and affects display of a first object, and the first object is a part, which is located in the depth distribution sub-region, of the content, wherein, adjusting the focal length of the first lenslet includes: determining, according to an expected focal length of the first lenslet, a phase difference that is formed after incident light passes through different parts of the first lenslet; determining, according to a mapping relationship between phase differences and external fields, an external field corresponding to the phase difference; and changing, by means of the external field, the phase difference that is formed after the incident light passes through the different parts of the first lenslet to adjust the focal length of the first lenslet.

17. The apparatus of claim 16 , wherein an average circle of confusion, in a first display plane of the light field display device, of the first object displayed by the first lenslet whose focal length has been adjusted is less than or equal to a permissible circle of confusion, and the first display plane is a display plane that is corresponding to a focusing distance for viewing in a depth direction and perpendicular to the depth direction.

18. The apparatus of claim 16 , wherein at least one of the at least one depth distribution sub-region is continuous in terms of depth with the display DoF range.

19. The apparatus of claim 16 , wherein at least one of the at least one depth distribution sub-region is discontinuous in terms of depth with the display DoF range.

20. The apparatus of claim 16 , wherein the operations further include: determining expected display depth information of the first object according to at least the display DoF range; and adjusting the focal length of the first lenslet according to at least the expected display depth information.

21. The apparatus of claim 20 , wherein the operations further include: determining any display depth in the display DoF range as the expected display depth information of the first object.

22. The apparatus of claim 20 , wherein the operations further include: determining a display depth, which is in the display DoF range and close to the depth distribution sub-region, as the expected display depth information of the first object according to a relative distribution of the depth distribution sub-region and the display DoF range in the depth direction.

23. The apparatus of claim 20 , wherein the operations further include: determining the expected focal length of the first lenslet according to the expected display depth information and a distance between a monitor and the lenslet array in the light field display device; and adjusting the focal length of the first lenslet according to at least the expected focal length.

24. The apparatus of claim 23 , wherein the operations further include: determining a permissible focal length adjustment range of the first lenslet according to at least the expected focal length; and adjusting the focal length of the first lenslet according to at least the permissible focal length adjustment range.

25. The apparatus of claim 24 , wherein the operations further include: determining according to the permissible focal length adjustment range, a permissible phase difference range that is formed after incident light passes through different parts of the first lenslet; determining according to a mapping relationship between phase differences and external fields, an external field corresponding to a permissible phase difference in the permissible phase difference range; and changing by means of the external field, a phase difference that is formed after the incident light passes through the different parts of the first lenslet, so as to adjust the focal length of the first lenslet.

26. The apparatus of claim 16 , wherein the operations further include: determining a lenslet which is in the lenslet array and affects display of the first object as the first lenslet.

27. The apparatus of claim 26 , wherein the operations further include: determining a first display sub-region according to expected display depth information, a focusing distance for viewing, and a pupil size of a human eye, wherein the first display sub-region is a display sub-region that is in the monitor of the light field display device and affects display of the first object; and determining, according to a mapping relationship between display sub-regions in the monitor and lenslets in the lenslet array, a lenslet which is in the lenslet array and corresponding to the first display sub-region as the first lenslet.

28. A light field display device, comprising: a monitor; a lenslet array, wherein the lenslet array includes multiple lenslets with adjustable focal lengths distributed in the array; and a light field display control apparatus of claim 16 , wherein the light field display control apparatus is connected to the monitor and the lenslet array.